=over

=item $#
X<$#>

C<$#> was a variable that could be used to format printed numbers.
After a deprecation cycle, its magic was removed in Perl v5.10.0 and
using it now triggers a warning: C<$# is no longer supported>.

This is not the sigil you use in front of an array name to get the
last index, like C<$#array>.  That's still how you get the last index
of an array in Perl.  The two have nothing to do with each other.

Deprecated in Perl 5.

Removed in Perl v5.10.0.

=back